Genetic Testing

Archive for the ‘Genetic Testing’ Category

Genetic Counseling | DNA Testing | Aurora Health Care

October 5th, 2018

Aurora Hereditary Cancer Prevention and Management Center (HCPMC)

Have genetic counseling and DNA testing determined that you or your family members have a hereditary cancer syndrome? Families with hereditary cancer syndromes are at high risk for multiple types of cancer. Even families whose genetic testing results are normal may be at increased risk for multiple cancers if they have complex cancer histories.

If your family history of cancer has been determined to be hereditary, or if your complex family history cant be explained by genetic testing, you deserve comprehensive care from a multidisciplinary team of experts in a single, convenient location.

The Aurora Hereditary Cancer Prevention and Management Center (HCPMC) specializes in testing and monitoring individuals and families with complex or difficult hereditary cancer conditions.

Through the HCPMC, you can:

If youre at risk for multiple types of cancer, ask your doctor for a referral to the Aurora Hereditary Cancer Prevention and Management Center in Milwaukee or Green Bay.

The HCPMC in Milwaukee is located within the Vince Lombardi Cancer Clinic at St. Lukes Medical Center. The HCPMC in Green Bay is located within the Vince Lombardi Cancer Clinic at Aurora BayCare Medical Center.

Call 877-647-2502 for more information.

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What is genetic testing? – Genetics Home Reference – NIH

September 24th, 2018

Genetic testing is a type of medical test that identifies changes in chromosomes, genes, or proteins. The results of a genetic test can confirm or rule out a suspected genetic condition or help determine a persons chance of developing or passing on a genetic disorder. More than 1,000 genetic tests are currently in use, and more are being developed.

Several methods can be used for genetic testing:

Chromosomal genetic tests analyze whole chromosomes or long lengths of DNA to see if there are large genetic changes, such as an extra copy of a chromosome, that cause a genetic condition.

Genetic testing is voluntary. Because testing has benefits as well as limitations and risks, the decision about whether to be tested is a personal and complex one. A geneticist or genetic counselor can help by providing information about the pros and cons of the test and discussing the social and emotional aspects of testing.

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Genetic Testing | ASCO

August 30th, 2018

Genetic testing can have implications for management of the cancer patients, including: surgical treatment, chemotherapy choices, prognosis and risk for additional cancers. It is therefore important to assess the risk of a hereditary syndrome at diagnosis, at decision points along the cancer treatment trajectory and again when entering survivorship or surveillance. An exhaustive list of implications of all cancer predisposition syndromes or germline alterations is beyond the scope of this toolkit; however we will provide some of the more common implications of identification of germline mutations in patients with cancer.

Genetic testing of a cancer assesses somatic genetic changes that may guide therapeutic choices (e.g., EGFR mutations for treatment of lung cancer). Some tumor (somatic) genetic testting will include mutations potentially inherited (germline) as well as those acquired in the tumor (somatic). Other genetic tests of the tumor will "subtract out" germline mutations by comparing mutations in the tumor to those found in sample of normal tissue or blood. It is important to understand which approach the genetic test you are reviewing has used. This toolkit does not address tumor somatic mutations. Germline genetic testing, usually performed on a blood sample, evaluates inherited genetic changes that increase the risk of certain cancers in an individual.

Benefits of Germline Genetic TestingGenetic testing can help identify cancers for which an individual is at increased risk. This increased risk can often be managed by increased surveillance, consideration of preventive medication or prophylactic surgery. In addition, identification of a familial germline mutation in a cancer susceptibility gene can alert family members who would also undergo genetic testing to clarify their own risk of cancer. Finally, identifying certain germline mutations may guide local and systemic treatment of a cancer (e.g., colectomy for a patient with colorectal cancer and Lynch syndrome; PARP inhibitor for a patient withovarian cancerwith aBRCA1/2mutation; avoidance of therapeutic radiation in a patient with breast cancerwith inheritedTP53mutation).

Germline mutations and second cancer risk: Second primary cancers occur in approximately 16% of all patients with cancer. Those individuals with strong family histories and/or pathogenic germline mutations in cancer-causing genes are at highest risk of second primary cancers. Genetic testing during survivorship or surveillance can identify those at greatest risk and action (more intense screening or preventive surgery) can be taken.

The guidelines below represent a selection of publicly available resources on genetic testing for specified cancer syndromes; this list is not exhaustive due to restrictions of member-only content. **Inclusion of third-party guidelines and recommendations should not be interpreted as formal endorsement by ASCO.**

Breast and Ovarian Cancer

Colorectal Cancer

Pre-implantation Genetic Testing | IVF Australia

August 22nd, 2018

What is pre-implantation genetic testing (PGT)?

Pre-implantation Genetic Testing (PGT) is a sophisticated scientific technique which can be used to test embryos for either a specific known genetic condition or chromosome abnormality.

This enables only chromosomally normal embryos or those unaffected by a specific disorder to be selected for transfer during an IVF cycle, maximising the chance of a healthy baby.

Up to 70% of embryos created, either via natural conception or IVF dont survive the first 3 months of pregnancy and many dont achieve implantation because of those two reasons.

IVFAustralia offers an internationally recognised pre-implantation genetics program, managed by Australias leading pre-implantation genetics laboratory Virtus Diagnostics.

You may wish to consider pre-implantation genetic testing if you are concerned about any of the following issues:

In pre-implantation genetic testing, the woman goes through a standard IVF cycle. While the embryos are developing in the IVF laboratory, a few cells are removed from each embryo and tested in one of two ways.

The technique of Next Generation Sequencing tests all 24 chromosomes in an embryo to enable the selection and transfer of only chromosomally healthy embryos.

Read more about PGT with Next Generation Sequencing >

Karyomapping is used if you or your partner are known to be carriers of a serious single gene disorder.

Karyomapping can identify which embryos are NOT affected by the disorder preventing the condition from being passed on to the next generation.

Genetic Testing: BRCA1, BRCA2, and PALB2 Mutations

July 5th, 2018

Three of the most well-known genes that can mutate and raise the risk of breast and/or ovarian cancer are BRCA1, BRCA2, and PALB2. Women who inherit a mutation, or abnormal change, in any of these genes from their mothers or their fathers have a much higher-than-average risk of developing breast cancer and/or ovarian cancer. (Abnormal PALB2 genes are suspected to raise the risk of ovarian cancer, but larger studies need to confirm that risk.) Men with these mutations have an increased risk of breast cancer, especially if the BRCA2 gene is affected, and possibly of prostate cancer. Many inherited cases of breast cancer have been associated with mutations in these three genes.

The function of the BRCA and PALB2 genes is to keep breast cells growing normally and prevent any cancer cell growth. But when these genes contain the mutations that are passed from generation to generation, they do not function normally and breast cancer risk increases. Abnormal BRCA1, BRCA2, and PALB2 genes may account for up to 10% of all breast cancers, or 1 out of every 10 cases.

Most people who develop breast cancer have no family history of the disease. However, when a strong family history of breast and/or ovarian cancer is present, there may be reason to believe that a person has inherited an abnormal gene linked to higher breast cancer risk. Some people choose to undergo genetic testing to find out. A genetic test involves giving a blood or saliva sample that can be analyzed to pick up any abnormalities in these genes.

In this section, you can read more about the following topics related to genetic testing:

If you want to learn more about family-related risk and genetics, you can visit the Lower Your Risk section of this site.

Researchers have discovered, and are continuing to discover, other abnormal genes that are less common than BRCA1, BRCA2, and PALB2 but also can raise breast cancer risk. Testing for these abnormalities is not done routinely, but it may be considered on the basis of your family history and personal situation. You can work with your doctor to decide whether testing for gene abnormalities besides BRCA1, BRCA2, and PALB2 is warranted.

The medical experts for Genetic Testing are:

These experts are members of the Breastcancer.org Professional Advisory Board, which includes more than 70 medical experts in breast cancer-related fields.

"Simply having a proven gene abnormality does not necessarily mean that a woman will develop breast cancer, or that her cancer will be any worse than cancer that does not stem from an inherited genetic flaw."

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Genetic Testing: BRCA1, BRCA2, and PALB2 Mutations

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Direct-to-Consumer Genetic Tests | Consumer Information

May 19th, 2018

Could a simple medical test tell you if you are likely to get a particular disease? Could it evaluate your health risks and even suggest a specific treatment? Could you take this test in the privacy of your home, without a doctors prescription or guidance?

Some companies say genetic testing can do all this and more. They claim that direct-to-consumer (DTC) genetic testing can screen for diseases and provide a basis for choosing a particular diet, dietary supplement, lifestyle change, or medication. These companies primarily sell their tests online and through multi-level marketing networks.

The Federal Trade Commission (FTC) wants you to know the facts about the DTC marketing of genetic tests.

According to the Food and Drug Administration (FDA), which regulates the manufacturers of genetic tests, and the Centers for Disease Control and Prevention (CDC), which promotes health and quality of life, some of these tests lack scientific validity, and others provide results that are meaningful only in the context of a full medical evaluation. The FDA and CDC say that due to the complexities of both the testing and the interpretation of the results, genetic tests should be conducted in registered laboratories that are certified to handle specimens, and the results may need to be interpreted by a doctor or trained counselor who understands the value of genetic testing for a particular situation.

Inside the cells of your body, chromosomes carry your genetic blueprint. Your chromosomes are passed to you by your parents; they contain genes made of DNA (deoxyribonucleic acid). Your genes determine characteristics like eye color or height, and contribute to your chances of getting certain diseases.

Genetic tests examine genes and DNA to see if they indicate the presence of, or risk for developing, particular diseases or disorders. Several different types of tests are available. Some look at the number and shape of chromosomes to find obvious abnormalities. Others look for small unusual portions of individual proteins or variations in DNA. Genetic tests might look at one or a few variations in DNA or a million or more variations at one time. Typically, these tests require a blood sample, a swab from inside your cheek, or saliva. In DTC genetic tests, you collect the sample at home and then send to a laboratory for analysis. No physicians prescription is required. Prices of DTC genetic tests can range from less than $100 to a few thousand dollars. Sometimes, they are offered for free as long as the consumer agrees to buy other products from the seller, like nutritional supplements.

The results of genetic tests are not always yes or no for the presence or the risk for developing disease, which make interpretations and explanations difficult. In most cases, diseases occur as a result of interaction among multiple genes and the environment for example, a persons lifestyle, the foods they eat, and the substances to which theyre exposed, like sunlight, chemicals, and tobacco. The interactions of these factors in contributing to health and disease can be very complex. Even health care experts are just beginning to understand the relationships among these factors. Thats why it is important to gather and analyze this information with a qualified health care provider so you can be sure genetic data is accurate and correctly used.

Many genetic tests look at only a small number of the more than 20,000 genes in the human body. A positive result means that the testing laboratory found unusual characteristics or changes in the genes it tested. Depending on the purpose of the test, a positive result may confirm a diagnosis, identify an increased risk of developing a disease, or indicate that a person is a carrier for a particular disease. It does not necessarily mean that a disease will develop, or if it does, that the disease will be progressive or severe.

A negative result means that the laboratory found no unusual characteristics or changes in the genes it tested. This could mean that a person doesnt have a particular disease, doesnt have an increased risk of developing the disease, or isnt a carrier of the disease. Or it could mean that the test didnt examine or has missed the specific genetic changes associated with a particular disease.

In short, the FDA and CDC say that genetic testing provides only one piece of information about a persons susceptibility to disease. Other factors, including family background, medical history, and environment, also contribute to the likelihood of getting a particular disease. In most cases, genetic testing makes the most sense when it is part of a medical exam that includes a persons family background and medical history.

Some companies claim that DTC genetic tests can measure the risk of developing a particular disease, like heart disease, diabetes, cancer, or Alzheimers. But the FDA and CDC say that risks of such diseases come from many sources, not just genetic changes, and that valid studies are necessary to prove these tests give accurate results. Having a particular gene variation doesnt necessarily mean that a disease will develop; likewise, not having a particular gene variation doesnt necessarily mean that the disease will not occur.

Some companies also may claim that a person can protect against serious disease by choosing special foods and nutritional supplements. Consequently, the results of their DTC genetic tests often include dietary advice and sales offers for customized dietary supplements and cosmetics. The FDA and CDC say they dont know of any valid scientific studies showing that genetic tests can be used safely or effectively to recommend nutritional choices or to genetically customize dietary supplements or cosmetics.

As for claims that the tests can assess a persons ability to withstand certain environmental exposures, like particular toxins or cigarette smoke: Be skeptical. The FDA and CDC arent aware of any valid scientific studies that show that genetic tests can be used to predict whether a person can withstand environmental exposures.

Some companies have claimed that DTC genetic tests can give information about how a persons body will respond to a certain treatment, and how well people will respond to a particular drug. This claim is based on current medical research that shows differences in drug effectiveness based on genetic make-up. But, say federal experts, while these tests may provide some information your doctor needs or uses to make treatment decisions for a specific condition, they are not a substitute for a physicians judgment and clinical experience.

According to the FDA and CDC, DTC genetic tests arent a suitable substitute for a traditional health care evaluation. Medical exams that include conventional laboratory tests like blood chemistry and lipid profiles are a more appropriate starting point for diagnosing diseases and assessing preventive measures. Nevertheless, if you are considering using a DTC genetic test:

The Federal Trade Commission works for the consumer to prevent fraudulent, deceptive, and unfair business practices in the marketplace and to provide information to help consumers spot, stop, and avoid them. To file a complaint or to get free information on consumer issues, visit ftc.gov or call toll-free, 1-877-FTC-HELP (1-877-382-4357); TTY: 1-866-653-4261.

The Food and Drug Administration is responsible for protecting the public health by assuring the safety, efficacy, and security of human and veterinary drugs, biological products, medical devices, our nations food supply, cosmetics, and products that emit radiation. The FDA also is responsible for advancing the public health by helping to speed innovations that make medicines and foods more effective, safer, and more affordable; and helping the public get the accurate, science-based information they need to use medicines and foods to improve their health. For more information from the FDA, call toll-free 1-800-INFO-FDA. Copies of press releases and consumer alerts are available from the FDAs website atwww.fda.gov.

The Centers for Disease Control and Prevention is one of the 13 major operating components of the Department of Health and Human Services, which is the principal agency in the United States government for protecting the health and safety of all Americans and for providing essential human services, especially for those people who are least able to help themselves. For further information about CDC,visit http://www.cdc.gov, call toll-free 1-800-CDC-INFO, or e-mailcdcinfo@cdc.gov.

Produced in cooperation with the Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC).

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Direct-to-Consumer Genetic Tests | Consumer Information

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Direct-to-consumer genetic testing kits – Harvard Health

May 19th, 2018

Published: September, 2010

You send in a sample and get your results online. But is it worth the price?

All disease is, to some degree, genetic. From cancer to the common cold, almost every human malady known to humankind has something to do with genes the stretches of DNA containing instructions for making the proteins that govern how our bodies are built and how they function. Your genes influence your risk for degenerative disorders the innumerable conditions from osteoporosis to Alzheimer's disease in which structure, function, or both deteriorate. They also influence allergic reactions, your ability to fend off infection, how you process nutrients and drugs, and even your susceptibility to accidents.

Trading on that knowledge and aided by technological advances that have improved the rate and accuracy of gene identification, a growing number of companies are marketing genetic testing kits directly to consumers. Their promotional materials promise to guide you to a healthier life by predicting your unique risk for developing scores of diseases and telling you how to prevent them.

The promise is enticing. Most of what we know about prevention and treatment is based on studies involving large numbers of people. Yet even the most successful regimens or therapies don't work for everyone. Genetic testing suggests the possibility of an approach to health care in which risk reduction and treatment are individually tailored. But buyer beware: while most scientists agree that the age of personalized medicine is on the horizon, many doubt that it's as close as the test-kit promotions would have you believe.

The Human Genome Project, completed in 2003, revealed just how much individual variation there is. Researchers worked out the order (or sequence) of the three billion DNA bases (chemical building blocks) that constitute the human genome (the complete set of human DNA). Although it's about 99% the same in all people, it still varies at more than 10 million DNA bases. That variation explains, in part, our varying degrees of risk for certain diseases.

In medical settings, genetic tests have been used to identify variations that cause serious health conditions. These tests are usually reserved for people known to be at risk for a specific disease because it runs in families. For example, couples planning a pregnancy may be tested to determine whether they carry the gene for Tay-Sachs disease. Women with close relatives who developed breast cancer early in life may want to know if they carry one of the high-risk BRCA genes. Because the results of such tests can alter lives, they are best administered only after individuals have been counseled on the risks, benefits, and limits of testing and have given informed consent. The results are confidential, and their implications should be explained to patients by genetic counselors.

Clinicians can also use genetic testing to help them select more effective drug treatments. For example, postmenopausal women with breast cancer for whom tamoxifen may be an option are sometimes tested to see if they have a gene variant that renders tamoxifen less effective; if they do, they can be prescribed a drug that works differently. Another genetic test may help determine whether patients at risk for blood clotting will benefit more from clopidogrel (Plavix) or from another drug such as prasugrel (Effient).

Direct-to-consumer genetic testing kits are marketed to people who aren't necessarily ill or at high risk for a disease, but who may be just curious or concerned about their risk for different disorders. Some of these tests require a physician's prescription, but many are sold directly to consumers on the Internet. The commercial tests examine a small number of the more than 20,000 genes in the human body and, in theory, predict your risk for conditions such as heart disease, colon cancer, and Alzheimer's disease; determine disease carrier status for pregnancy planning; and identify genetic variants that increase or decrease your ability to metabolize alcohol and certain drugs. Many also offer ancestry tracking identifying clusters of gene variations that are often inherited by a group of people with a common origin.

If you want to take a test, you will need an e-mail account and Internet access. After registering (and paying with a credit card) through the company's Web site, you'll be mailed a kit with instructions for collecting cells through saliva or a cheek swab. You mail the sample to a lab where it is analyzed and you receive a report within a specified time. Material accompanying your report may recommend strategies for reducing your risk of developing the condition your genes predict. You may also get telephone or e-mail access to a genetic counselor.

Commercial genetic tests are under scrutiny by the federal government. When Pathway Genomics announced in May 2010 that it would market its test kits through Walgreens drugstores, a Congressional committee launched an investigation. Meanwhile, the FDA has notified several consumer genetic-testing companies that they must apply for approval of the tests as medical devices (or explain why they think approval is unnecessary). The concern is that the companies are making scientifically unsupportable claims for the value of the tests in making health decisions. Walgreens has postponed plans to sell Pathway's kits in stores, and the investigations may force some changes in the way these tests are marketed.

If you're considering ordering a test kit, keep the following in mind:

They're expensive. The cost can run to several hundred dollars or more (see the chart, below), and it's not covered by insurance.

Your report will be based on incomplete knowledge. Your risk for conditions like heart disease, diabetes, and cancer depends on complex interactions between genes and lifestyle factors. Even diseases caused by a single gene, such as cystic fibrosis, are influenced by other genes that can affect, for example, the condition's severity. Researchers haven't identified all the genes responsible for these conditions or determined how factors such as diet or exercise influence the expression of those genes. Moreover, in many cases, the gene variations identified by the tests are only slightly associated with risk, or there is little good evidence to support any association.

The effects of a gene variation usually depend on other hereditary factors. It's important to get as much information as you can about members of your family and interpret the test results in that context. For example, if your father had a heart attack, did it occur at age 40 or age 80? The online test kits can't take that information into account.

Most of the tests have not been clinically validated. It will take large studies to determine whether the gene variations used in these tests accurately predict disease.

The test may not tell you anything you don't already know. By middle age, medical exams and screenings have probably given you a good idea of your risk for heart disease, diabetes, or osteoporosis. If you're uncertain, you can consult one of the well-established cost-free risk calculators, which include the Framingham Risk Assessment Tool for heart disease (www.health.harvard.edu/heartrisk), the Diabetes Risk Test (www.diabetes.org), and the FRAX tool, which estimates the 10-year likelihood of a hip or other major fracture (www.shef.ac.uk/FRAX).

Knowing the results won't always be useful. Identifying a genetic risk may inspire you to adopt a more healthful lifestyle, but it could also prompt you to seek diagnostic tests you don't need. It could even make you fatalistic and discouraged. Correspondingly, the absence of a genetic risk could create a false sense of security.

The follow-up report offers mostly generic advice. You may find that the payoff your personal guide to better health is a letdown. The recommendations are likely to be very similar to guidelines set by the Centers for Disease Control and Prevention or the National Institutes of Health, which are based on large-group or population-wide studies.

Company (Web site)

Sample

Conditions

Price

deCODE genetics(www.decodeme.com)

Cheek swab

Carrier status for disorders, disease risk, drug metabolism, ancestry

$2000 for complete panel; $500 each, cancer or heart panel. Genetic counseling included in price.

23andMe, Inc.(www.23andme.com)

Saliva

Carrier status for disorders, disease risk, drug metabolism, ancestry

$429 for health panel (carrier status, disease risk, drug metabolism); $399 for ancestry; $499 for both. Genetic counseling available for additional fee.

Pathway Genomics*(www.pathway.com)

Saliva

Carrier status for pregnancy planning, disease risk, drug metabolism, ancestry

$399 for disease risk panel; $249 each for ancestry, pregnancy planning, drug metabolism. Genetic counseling included in price.

Interleukin Genetics(www.ilgenetics.com)

Cheek swab

Obesity, heart attack, B vitamin metabolism, bone loss

$149 each; discounted prices for two or more. Genetic counseling and consultation included in price.

*Disclosure: Harvard Health Publishing, publishers of Harvard Women's Health Watch, has a licensing agreement with Pathway Genomics unrelated to this article.

If you're still interested in ordering a genetic test kit, start by exploring the company Web site for answers to these questions:

How accurate are the results? This depends on the quality of the sample and the reliability of the laboratory performing the analysis. You'll want to know what the company will do if your sample is unusable. Some will refund your payment; others will let you submit another sample. You will also want to make sure that the lab is accredited. In the United States, most clinical labs are certified by the Center for Medicare and Medicaid Services.

How will I know what my results mean? Most Web sites provide sample reports that allow you to judge the quality of the explanation and advice you'll get. The Web site should also tell you whether you can get help interpreting the results from a medical geneticist or a genetics counselor.

Will my results and any risk-reduction strategies be useful? Most reports will indicate which genetic variations you have and offer a general idea of what they mean. The risks of developing specific disorders will usually be given as a percentage above or below average or characterized as "high," "low" or "average." You should ask yourself whether you really want to know if you're even at slightly elevated risk for a serious disease you can do nothing to prevent, such as amyotrophic lateral sclerosis, or ALS, better known as Lou Gehrig's disease.

Is my information confidential? Under the Genetic Information Nondiscrimination Act, you cannot be denied a job or health insurance on the basis of your genetic information except in companies with fewer than 15 employees. The law does not apply to life, disability, or long-term care insurance. Be sure to find out about how your sample will be stored. If you're using an online test, your results should be presented on a secure server, anonymously stored, and password protected.

Someday everyone's genome may be sequenced as a matter of course, and the information used to guide our health decisions and medical care through life. But at present there is no direct evidence that these tests offer any practical benefits; that's why they aren't covered by health insurance. Genetically individualized medicine will have its day only when the predictive power of the tests improves and the cost of sequencing an individual's complete genome falls from its current level of $10,000 to $15,000 to a level where it's practical for large-scale use.

Right now, almost everything these tests offer is also available through medical professionals. If you think your genes put you at higher-than-average risk for certain diseases, talk to your clinician or a genetic counselor. A face-to-face counseling session will be far more informative and personal than an online testing kit, and it may even be covered by your health insurance.

If you're interested in acquiring your personal genome, consider applying to the Personal Genome Project at http://www.personalgenomes.org. It's an open-ended study aimed at matching gene variations with diseases in 100,000 people. And don't overlook the low-tech approach to genetics. Compile a medical history of your family in as much detail and for as many generations as possible. Then, if your genome becomes available, you'll have a context to place it in.

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Genetic Testing – KidsHealth

May 5th, 2018

Genetic tests are done by analyzing small samples of blood or body tissues. They determine whether you, your partner, or your baby carry genes for certain inherited disorders.

Genetic testing has developed enough so that doctors can often pinpoint missing or defective genes. The type of genetic test needed to make a specific diagnosis depends on the particular illness that a doctor suspects.

Many different types of body fluids and tissues can be used in genetic testing. For deoxyribonucleic acid (DNA) screening, only a very tiny bit of blood, skin, bone, or other tissue is needed.

For genetic testing before birth, pregnant women may decide toundergo amniocentesis or chorionic villus sampling. There is also a blood test available to women to screen for some disorders. If this screening test finds a possible problem, amniocentesis or chorionic villus sampling may be recommended.

Amniocentesis is a test usually performed between weeks 15 and 20of a woman's pregnancy. The doctor inserts a hollow needle into the woman's abdomen to remove a small amount of amniotic fluid from around the developing fetus. This fluid can be tested to check for genetic problems and to determine the sex of the child. When there's risk of premature birth, amniocentesis may be done to see how far the baby's lungs have matured. Amniocentesis carries a slight risk of inducing a miscarriage.

Chorionic villus sampling (CVS) is usually performed between the 10th and 12th weeks of pregnancy. The doctor removes a small piece of the placenta to check for genetic problems in the fetus. Because chorionic villus sampling is an invasive test, there's a small risk that it can induce a miscarriage.

A doctor may recommend genetic counseling or testing for any of the following reasons:

Although advances in genetic testing have improved doctors' ability to diagnose and treat certain illnesses, there are still some limits. Genetic tests can identify a particular problem gene, but can't always predict how severely that gene will affect the person who carries it. In cystic fibrosis, for example, finding a problem gene on chromosome number 7 can't necessarily predict whether a child will have serious lung problems or milder respiratory symptoms.

Also, simply having problem genes is only half the story because many illnesses develop from a mix of high-risk genes and environmental factors. Knowing that you carry high-risk genes may actually be an advantage if it gives you the chance to modify your lifestyle to avoid becoming sick.

As research continues, genes are being identified that put people at risk for illnesses like cancer, heart disease, psychiatric disorders, and many other medical problems. The hope is that someday it will be possible to develop specific types of gene therapy to totally prevent some diseases and illnesses.

Gene therapy is already being studied as a possible way to treat conditions like cystic fibrosis, cancer, and ADA deficiency (an immune deficiency), sickle cell disease, hemophilia, and thalassemia. However, severe complications have occurred in some patients receiving gene therapy, so current research with gene therapy is very carefully controlled.

Although genetic treatments for some conditions may be a long way off, there is still great hope that many more genetic cures will be found. The Human Genome Project, which was completed in 2003, identified and mapped out all of the genes (about 25,000) carried in our human chromosomes. The map is just the start, but it's a very hopeful beginning.

Date reviewed: April 2014

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The Universe of Genetic Testing | Lab Tests Online

May 5th, 2018

Clinical genetic testing refers to the laboratory analysis ofDNAorRNAto aid in the diagnosis of disease. It is very important to understand that clinical genetic testing is quite different than other types of laboratory tests. Genetic testing is unique in that it can provide definitive diagnosis as well as help predict the likelihood of developing a particular disease before symptoms even appear; it can tell if a person is carrying a specific gene that could be passed on to his or her children; it can inform as to whether some treatments will work before a patient starts therapy. These are definite advantages. However, there are also some qualities of genetic testing that should be carefully thought out and perhaps discussed with agenetic counselorbefore undergoing any test. These aspects are reviewed in the section titledPros and Cons of Genetic Testing. In an era of patient responsibility, it is important that you be educated in these matters to fully appreciate the value as well as the drawbacks of genetic testing.

Testing Genetic Material

Testing of genetic material is performed on a variety of specimens including blood, urine, saliva, stool, body tissues, bone, or hair. Cells in these samples are isolated and the nucleic acids (DNA or sometimes RNA) within them is extracted and examined for possiblemutationsor alterations. Looking at small portions of the DNA within agenerequires specialized and specific laboratory testing. This is done to pinpoint the exact location of genetic errors. This section will focus on the examination of a person's genes to look for the one(s) responsible for a particular disease.

There are four basic reasons that genetic material is tested for clinical reasons. Presymptomatic testing identifies the presence of variant genes that cause disease even if the physical abnormalities associated with the disease are not yet present in an individual. Diagnostic genetic testing is performed on a symptomatic individual with symptoms sufficiently suggestive of a genetic disorder. This assists the individuals physician in making a clear diagnosis.

Testing of genetic material can also be performed as a prenatal screening tool to assess whether two individuals who wish to become parents have an autosomal orX-linked recessivegene that, when combined in a child, will produce a serious disorder in that child. This type of genetic testing is referred to ascarrierscreening. Fetuses developing in the uterus can also have their genetic material tested to assess their health status if it is thought to be in jeopardy.

To test DNA for medical reasons, some type of cellular material is required. This material can come from blood, urine, saliva, body tissues, bone marrow, hair, etc. The material can be submitted in a tube, on a swab, in a container, or frozen. If the test requires RNA, the same materials can be used. Once received in the laboratory, the cells are removed from the substance they are in, broken apart, and the DNA in thenucleiis isolated and extracted.

The laboratory professionals who perform and interpret these tests are specially trained physicians and scientists. The extracted DNA is manipulated in different ways in order for the molecular pathologist or genetic technologist to see what might be missing or mutated in such a way as to cause disease. One type of manipulation is "cutting" the DNA into small pieces using specialenzymes. These small pieces are much easier to test than the long strands of uncut DNA and they contain the genes of interest. Another manipulation is to apply the extracted and cut DNA to an agarose gel, apply an electrical field to the gel, and see how the DNA moves on the gel. This can indicate differences in the size of the pieces of the cut DNA that might be caused by specific mutations.

Other manipulations to DNA includeamplification, sequencing, or a special procedure called hybridization. When the results of these tests are examined and compared with results from a normal person, it is possible to see differences in the genes that might cause a disease.

Specific Genetic DiseasesThere are many diseases that are now thought to be caused by alterations in DNA. These alterations can either be inherited or can occur spontaneously. Some diseases that have a genetic component to them include:

Alzheimer's DiseaseBone Marrow DisordersBreast Cancer

Ovarian CancerColon CancerCystic Fibrosis

Down SyndromeHemochromotosisLeukemia

LupusLymphomaOsteoarthritis

Pre-senilin MutationSickle Cell AnemiaThalassemia

Several things can go wrong with the genes that make up the DNA, resulting in these and other diseases. The section below discusses what can happen to DNA, and specifically to genes, that might lead to a disease.

Genetic Variation and MutationAll genetic variations or polymorphisms originate from the process of mutation. Genetic variations occur sometimes during the process ofsomatic celldivision (mitosis). Other genetic variations can occur during meiosis, the cycle of division that a sperm cell or anovumgoes through. Some variations are passed along through the generations, adding more and more changes over the years. Sometimes these mutations lead to disease; other times there is no noticeable effect. Genetic variations can be classified into different categories: stable genetic variations, unstable genetic variations, silent genetic variations, and other types.

Stable genetic variations are caused by specific changes in single nucleotides. These changes are called single nucleotide polymorphisms or SNPs and can include:

If the SNP causes a new amino acid to be made, it is called a "missense mutation." An example of this is in sickle cell anemia, in which one nucleotide is substituted for another. The genetic variation in the gene causes a different amino acid to be added to a protein, resulting in a protein that doesn't do its job properly and causes cells to form sickle shapes and not carry oxygen.

Unstable genetic variations occur when a nucleotide sequence repeats itself over and over. This is called a "repeat" and is usually normal; however, if the number of repeats increases too greatly, it is called an "expanded repeat" and has been found to be the cause of many genetic disorders. An example of a disease caused by an expanded repeat isHuntington disease, a severe disorder of a part of the brain that is marked by dementia, hydrocephalus, and unusual movements.

Silent genetic variations are those mutations or changes in a gene that do not change the protein product of the gene. These mutations rarely result in a disease.

Other types of variations occur when an entire gene is duplicated somewhere in a person's genome. When this occurs, extra copies of the gene are present and make extra protein product. This is seen in a disorder that effects peripheral nerves and is called Charcot-Marie-Tooth disease type 1. Some variations occur in a special part of the gene that controls when DNA is copied to RNA. When the timing of protein production is thrown off, it results in decreased protein production. Other variations include a defect in a gene that makes a protein that serves to repair broken DNA in our cells. This variation can result in many types of diseases, including colorectal cancer and a skin disease called xeroderma pigmentosum.

Testing for Products of Genetic ExpressionMany inherited disorders are identified indirectly by examining abnormalities in the genetic end products (proteinsormetabolites) that are present in abnormal forms or quantities. As a reminder, genes code for the production of thousands of proteins and, if there is an error in the code, changes can occur in the production of those proteins. So, rather than detecting the problem in the gene, some types of testing look for unusual findings related to the pertinent proteins, such as their absence.

An example of testing for genetic products includes those widely used to screen newborns for a variety of disorders. For example, newborns are tested for phenylketonuria (PKU), an inherited autosomal recessive metabolic disorder caused by a variation in a gene that makes a special enzyme that breaks down phenylalanine, an amino acid. When too much of this substance builds up in blood, it can lead to mental retardation if not treated early in life with a special, restricted diet. The test uses a blood sample from a baby's heel to look for the presence of extra phenylalanine, rather than looking for the mutated gene itself. Other examples include blood tests for congenital hypothyroidism, diagnosed by low blood levels or absence of thyroid hormone, and congenital adrenal hyperplasia, a genetic disease that causes the hormone cortisol to be decreased in blood. Frequently, abnormal blood screening tests in the newborn may be augmented by genetic testing when appropriate (in cystic fibrosis, for example).

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The Universe of Genetic Testing | Lab Tests Online

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Genealogical DNA test – Wikipedia

May 5th, 2018

A genealogical DNA test is a DNA-based test which looks at specific locations of a person's genome in order to determine ancestral ethnicity and genealogical relationships. Results give information about ethnic groups the test subject may be descended from and about other individuals that they may be related to.

Three principal types of genealogical DNA tests are available, with each looking at a different part of the genome and useful for different types of genealogical research: Autosomal, Mitochondrial, and Y. In general, genealogical DNA tests do not give information about medical conditions or diseases.

The first company to provide direct-to-consumer genetic DNA testing was the now defunct GeneTree. However, it did not offer multi-generational genealogy tests. In fall 2001, GeneTree sold its assets to Salt Lake City-based Sorenson Molecular Genealogy Foundation (SMGF) which originated in 1999.[1] While in operation, SMGF provided free Y-Chromosome and mitochondrial DNA tests to thousands.[2] Later, GeneTree returned to genetic testing for genealogy in conjunction with the Sorenson parent company and eventually was part of the assets acquired in the Ancestry.com buyout of SMGF.[3]

In 2000, Family Tree DNA, founded by Bennett Greenspan and Max Blankfeld, was the first company dedicated to direct-to-consumer testing for genealogy research. They initially offered eleven marker Y-Chromosome STR tests and HVR1 mitochondrial DNA tests. They originally tested in partnership with the University of Arizona.[4][5] [6] [7] [8]

In 2007, 23andMe was the first company to offer a saliva-based direct-to-consumer genetic testing[9]. It was also the first to implement using autosomal DNA for ancestry testing, which all other major companies now use.[10][11]

In 2018 it was estimated that over 12 million people had had their DNA tested for genealogical purposes, most of whom were in the USA.[12]

A genealogical DNA test is performed on a DNA sample. This DNA sample can be obtained by a cheek-scraping (also known as a buccal swab), spit-cups, mouthwash, and chewing gum. Typically, the sample collection uses a home test kit supplied by a service provider such as Anglia DNA Services, 23andMe, AncestryDNA, Family Tree DNA, MyHeritage, or National Geographic Genographic Project). After following the kit instructions on how to collect the sample, it is returned to the supplier for analysis.

There are three major types of genealogical DNA tests: Autosomal and X-DNA, Y-DNA and mtDNA.

Y-DNA and mtDNA cannot be used for ethnicity estimates, but can be used to find one's haplogroup, which is unevenly distributed geographically.[14] Direct-to-consumer DNA test companies have often labeled haplogroups by continent or ethnicity (e.g., an "African haplogroup" or a "Viking haplogroup"), but these labels may be speculative or misleading.[14][15][16]

Autosomal DNA is contained in the 22 pairs of chromosomes not involved in determining a person's sex.[14] Autosomal DNA recombines each generation, and new offspring receive one set of chromosomes from each parent.[17] These are inherited exactly equally from both parents and roughly equally from grandparents to about 3x great-grand parents.[18] Therefore, the number of markers (one of two or more known variants in the genome at a particular location known as Single-nucleotide polymorphisms or SNPs) inherited from a specific ancestor decreases by about half each generation; that is, an individual receives half of their markers from each parent, about a quarter of their markers from each grandparent; about an eighth of their markers from each great grandparent, etc. Inheritance is more random and unequal from more distant ancestors.[19] Generally, a genealogical DNA test might test about 700,000 SNPs (specific points in the genome).[20]

The preparation of a report on the DNA in the sample proceeds in multiple stages:

All major service providers use equipment with chips supplied by Illumina.[21] The chip determines which SNP locations are tested. Different versions of the chip are used by different service providers. In addition, updated versions of the Illumina chip may test different sets of SNP locations. The list of SNP locations and base pairs at that location is usually available to the customer as "raw data". The raw data can sometimes be uploaded to another service provider to produce an additional interpretation and matches. For additional analysis the data can also be uploaded to GEDmatch (a third-party web based set of tools that analyzes raw data from the main service providers).

The major component of an autosomal DNA test is matching other individuals. Where the individual being tested has a number of consecutive SNPs in common with a previously tested individual in the company's database, it can be inferred that they share a segment of DNA at that part of their genomes.[22] If the segment is longer than a threshold amount set by the testing company, then these two individuals are considered to be a match. Unlike the identification of base pairs, the data bases against which the new sample is tested, and the algorithms used to determine a match, are proprietary and specific to each company.

The unit for segments of DNA is the centimorgan (cM). For comparison, a full human genome is about 6500 cM. The shorter the length of a match, the greater are the chances that a match is spurious.[23] An important statistic for subsequent interpretation is the length of the shared DNA (or the percentage of the genome that is shared).

Most companies will show the customers how many cMs they share, and across how many segments. From the number of cMs and segments, the relationship between the two individuals can be estimated, however due to the random nature of DNA inheritance, relationship estimates, especially for distant relatives, are only approximate. Some more distant cousins will not match at all.[24] Although information about specific SNPs can be used for some purposes (eg suggesting likely eye colour), the key information is the percentage of DNA shared by 2 individuals. This can indicate the closeness of the relationship. However, it does not show the roles of the 2 individuals - eg 50% shared suggests a parent - child relationship, but does not identify which individual is the parent.

Various advanced techniques and analysis can be done on this data. This includes features such as In-common/Shared Matches,[25] Chromosome Browsers[26] and Triangulation[27]. This analysis is often required if DNA evidence is being used to prove or disprove a specific relationship.

The X-chromosome SNP results are often included in Autosomal DNA tests. Both males and females receive an X-chromosome from their mother, but only females receive a second X-chromosome from their father.[28] The X-chromosome has a special path of inheritance patterns and can be useful in significantly narrowing down possible ancestor lines compared to atDNA for example an X-chromosome match with a male can only have come from his maternal side.[29] Like autosomal DNA, X-chromosome DNA undergoes random recombination at each generation (except for father to daughter X-chromosomes which are passed down unchanged). There are specialised inheritance charts which describe the possible patterns of X-chromosome DNA inheritance for males and females.[30]

Some genealogical companies offer autosomal STRs (short tandem repeats). These are similar to Y-DNA STRs. The number of STRs offered is limited, and not genealogically useful.

The mitochondrion is a component of a human cell, and contains its own DNA. Mitochondrial DNA usually has 16,569 base pairs (the number can vary slightly depending on addition or deletion mutations)[31] and is much smaller than the human genome DNA which has 3.2 billion base pairs. Mitochondrial DNA is transmitted from mother to child, thus a direct maternal ancestor can be traced using mtDNA. The transmission occurs with relatively rare mutations compared to the genome DNA. A perfect match found to another person's mtDNA test results indicates shared ancestry of possibly between 1 and 50 generations ago.[14] More distant matching to a specific haplogroup or subclade may be linked to a common geographic origin.

There is debate over whether or not paternal mtDNA transmission is possible in humans. Some authors cite paternal mtDNA transmission as invalidating mtDNA testing.[32] However, other studies hold that paternal mtDNA is never transmitted to offspring,[33] which would validate the use of mTDNA testing for genealogy.

mtDNA, by current conventions, is divided into three regions. They are the coding region (00577-16023) and two Hyper Variable Regions (HVR1 [16024-16569], and HVR2 [00001-00576]).[34]

The two most common mtDNA tests are a sequence of HVR1 and HVR2 and a full sequence of the mitochondria. Generally, testing only the HVRs has limited genealogical use so it is increasingly popular and accessible to have a full sequence. The full sequence is somewhat controversial because the coding region DNA may reveal medical information about the test-taker.[35]

All humans descend in the direct female line from Mitochondrial Eve, a female who lived probably around 200,000 years ago in Africa. Different branches of her descendants are different haplogroups. Most mtDNA results include a prediction or exact assertion of one's mtDNA Haplogroup. Mitochrondial haplogroups were greatly popularized by the book The Seven Daughters of Eve, which explores mitochondrial DNA.

It is not normal for test results to give a base-by base list of results. Instead, results are normally compared to the Cambridge Reference Sequence (CRS), which is the mitochondria of a European who was the first person to have their mtDNA published in 1981 (and revised in 1999).[36] Differences between the CRS and testers are usually very few, thus it is more convenient than listing one's raw results for each base pair.

Note that in HVR1, instead of reporting the base pair exactly, for example 16,111, the 16 is often removed to give in this example 111. The Letters refer to one of the 4 bases (A, T, G, C) that make up human DNA.

mtDNA testing was used by University of Leicester archaeologists to verify the skeletal remains of King Richard III, found in September 2012.[37]

The Y-Chromosome is one of the 23rd pair of human chromosomes. Only males have a Y-chromosome, because women have two X chromosomes in their 23rd pair. A man's patrilineal ancestry, or male-line ancestry, can be traced using the DNA on his Y chromosome (Y-DNA), because the Y-chromosome is transmitted father to son nearly unchanged.[38] A man's test results are compared to another man's results to determine the time frame in which the two individuals shared a most recent common ancestor, or MRCA, in their direct patrilineal lines. If their test results are very close, they are related within a genealogically useful time frame.[39] A surname project is where many individuals whose Y-chromosomes match collaborate to find their common ancestry.

Women who wish to determine their direct paternal DNA ancestry can ask their father, brother, paternal uncle, paternal grandfather, or a paternal uncle's son (their cousin) to take a test for them.

There are two types of DNA testing: STRs and SNPs.[14]

Most common is STRs (short tandem repeat). A certain section of DNA is examined for a pattern that repeats (e.g. ATCG). The number of times it repeats is the value of the marker. Typical tests test between 12 and 111 STR markers. STRs mutate fairly frequently. The results of two individuals are then compared to see if there is a match. Close matches may join a surname project. DNA companies will usually provide an estimate of how closely related two people are, in terms of generations or years, based on the difference between their results.[40]

A person's haplogroup can often be inferred from their STR results, but can be proven only with a Y-chromosome SNP tests (Y-SNP test).

A single-nucleotide polymorphism (SNP) is a change to a single nucleotide in a DNA sequence. Typical Y-DNA SNP tests test about 20,000 to 35,000 SNPs.[41] Getting a SNP test allows a much higher resolution than STRs. It can be used to provide additional information about the relationship between two individuals and to confirm haplogroups.

All human men descend in the paternal line from a single man dubbed Y-chromosomal Adam, who lived probably between 200,000 and 400,000 years ago. A 'family tree' can be drawn showing how men today descend from him. Different branches of this tree are different haplogroups. Most haplogroups can be further subdivided multiple times into sub-clades. Some known sub-clades were founded in the last 1000 years, meaning their timeframe approaches the genealogical era (c.1500 onwards).[42]

New sub-clades of haplogroups may be discovered when an individual tests, especially if they are non-European. Most significant of these new discoveries was in 2013 when the haplogroup A00 was discovered, which required theories about Y-chromosomal Adam to be significantly revised. The haplogroup was discovered when an African-American man tested STRs at FamilyTreeDNA and his results were found to be unusual. SNP testing confirmed that he does not descend patrilineally from the "old" Y-chromosomal Adam and so a much older man became Y-Chromosomal Adam.

Many companies offer a percentage breakdown by ethnicity or region. Generally the world is specified into about 2025 regions, and the approximate percentage of DNA inherited from each is stated. This is usually done by comparing the frequency of each Autosomal DNA marker tested to many population groups.[14] The reliability of this type of test is dependent on comparative population size, the number of markers tested, the ancestry informative value of the SNPs tested, and the degree of admixture in the person tested. Earlier ethnicity estimates were often wildly inaccurate, but their accuracies have since improved greatly.[citation needed] Usually the results at the continental level are accurate, but more specific assertions of the test may turn out to be incorrect. For example, Europeans often receive an exaggerated proportion of Scandinavian.[43] Testing companies will often regularly update their ethnicity estimate, changing an individual's ethnicity estimate.

The interest in genealogical DNA tests has been linked to both an increase in curiosity about traditional genealogy and to more general personal origins. Those who test for traditional genealogy often utilize a combination of autosomal, mitochondrial, and Y-Chromosome tests. Those with an interest in personal ethnic origins are more likely to use an autosomal test. However, answering specific questions about the ethnic origins of a particular lineage may be best suited to an mtDNA test or a Y-DNA test.

For recent genealogy, exact matching on the mtDNA full sequence is used to confirm a common ancestor on the direct maternal line between two suspected relatives. Because mtDNA mutations are very rare, a nearly perfect match is not usually considered relevant to the most recent 1 to 16 generations.[44] In cultures lacking matrilineal surnames to pass down, neither relative above is likely to have as many generations of ancestors in their matrilineal information table as in the above patrilineal or Y-DNA case: for further information on this difficulty in traditional genealogy, due to lack of matrilineal surnames (or matrinames), see Matriname.[45] However, the foundation of testing is still two suspected descendants of one person. This hypothesize and test DNA pattern is the same one used for autosomal DNA and Y-DNA.

As discussed above, autosomal tests usually report the ethnic proportions of the individual. These attempt to measure an individual's mixed geographic heritage by identifying particular markers, called ancestry informative markers or AIM, that are associated with populations of specific geographical areas. Geneticist Adam Rutherford has written that these tests "dont necessarily show your geographical origins in the past. They show with whom you have common ancestry today."[46]

The haplogroups determined by Y-DNA and mtDNA tests are often unevenly geographically distributed. Many direct-to-consumer DNA tests described this association to infer the test-taker's ancestral homeland.[16] Most tests describe haplogroups according to their most frequently associated continent (e.g., a "European haplogroup").[16] When Leslie Emery and collaborators performed a trial of mtDNA haplogroups as a predictor of continental origin on individuals in the Human Genetic Diversity Panel (HGDP) and 1000 Genomes (1KGP) datasets, they found that only 14 of 23 haplogroups had a success rate above 50% among the HGDP samples, as did "about half" of the haplogroups in the 1KGP.[16] The authors concluded that, for most people, "mtDNA-haplogroup membership provides limited information about either continental ancestry or continental region of origin."[16]

Y-DNA and mtDNA testing may be able to determine with which peoples in present-day Africa a person shares a direct line of part of his or her ancestry, but patterns of historic migration and historical events cloud the tracing of ancestral groups. Due to joint long histories in the US, approximately 30% of African American males have a European Y-Chromosome haplogroup[47] Approximately 58% of African Americans have at least the equivalent of one great-grandparent (13%) of European ancestry. Only about 5% have the equivalent of one great-grandparent of Native American ancestry. By the early 19th century, substantial families of Free Persons of Color had been established in the Chesapeake Bay area who were descended from free people during the colonial period; most of those have been documented as descended from white men and African women (servant, slave or free). Over time various groups married more within mixed-race, black or white communities.[48]

According to authorities like Salas, nearly three-quarters of the ancestors of African Americans taken in slavery came from regions of West Africa. The African-American movement to discover and identify with ancestral tribes has burgeoned since DNA testing became available. African Americans usually cannot easily trace their ancestry during the years of slavery through surname research, census and property records, and other traditional means. Genealogical DNA testing may provide a tie to regional African heritage.

Melungeons are one of numerous multiracial groups in the United States with origins wrapped in myth. The historical research of Paul Heinegg has documented that many of the Melungeon groups in the Upper South were descended from mixed-race people who were free in colonial Virginia and the result of unions between the Europeans and Africans. They moved to the frontiers of Virginia, North Carolina, Kentucky and Tennessee to gain some freedom from the racial barriers of the plantation areas.[49] Several efforts, including a number of ongoing studies, have examined the genetic makeup of families historically identified as Melungeon. Most results point primarily to a mixture of European and African, which is supported by historical documentation. Some may have Native American heritage as well. Though some companies provide additional Melungeon research materials with Y-DNA and mtDNA tests, any test will allow comparisons with the results of current and past Melungeon DNA studies

The pre-columbian indigenous people of the United States are called "Native Americans" in American English.[50] Autosomal testing, Y-DNA, and mtDNA testing can be conducted to determine the ancestry of Native Americans. A mitochondrial Haplogroup determination test based on mutations in Hypervariable Region 1 and 2 may establish whether a person's direct female line belongs to one of the canonical Native American Haplogroups, A, B, C, D or X. The vast majority of Native American individuals belong to one of the five identified mtDNA Haplogroups. Thus, being in one of those groups provides evidence of potential Native American descent. However, DNA ethnicity results cannot be used as a substitute for legal documentation.[51] Native American tribes have their own requirements for membership, often based on at least one of a person's ancestors having been included on tribal-specific Native American censuses (or final rolls) prepared during treaty-making, relocation to reservations or apportionment of land in the late 19th century and early 20th century. One example is the Dawes Rolls.

The Cohanim (or Kohanim) is a patrilineal priestly line of descent in Judaism. According to the Bible, the ancestor of the Cohanim is Aaron, brother of Moses. Many believe that descent from Aaron is verifiable with a Y-DNA test: the first published study in genealogical Y-Chromosome DNA testing found that a significant percentage of Cohens had distinctively similar DNA, rather more so than general Jewish or Middle Eastern populations. These Cohens tended to belong to Haplogroup J, with Y-STR values clustered unusually closely around a haplotype known as the Cohen Modal Haplotype (CMH). This could be consistent with a shared common ancestor, or with the hereditary priesthood having originally been founded from members of a single closely related clan.

Nevertheless, the original studies tested only six Y-STR markers, which is considered a low-resolution test. In response to the low resolution of the original 6-marker CMH, the testing company FTDNA released a 12-marker CMH signature that was more specific to the large closely related group of Cohens in Haplogroup J1.

A further academic study published in 2009 examined more STR markers and identified a more sharply defined SNP haplogroup, J1e* (now J1c3, also called J-P58*) for the J1 lineage. The research found "that 46.1% of Kohanim carry Y chromosomes belonging to a single paternal lineage (J-P58*) that likely originated in the Near East well before the dispersal of Jewish groups in the Diaspora. Support for a Near Eastern origin of this lineage comes from its high frequency in our sample of Bedouins, Yemenis (67%), and Jordanians (55%) and its precipitous drop in frequency as one moves away from Saudi Arabia and the Near East (Fig. 4). Moreover, there is a striking contrast between the relatively high frequency of J-58* in Jewish populations (20%) and Kohanim (46%) and its vanishingly low frequency in our sample of non-Jewish populations that hosted Jewish diaspora communities outside of the Near East."[52]

Recent phylogenetic research for haplogroup J-M267 placed the "Y-chromosomal Aaron" in a subhaplogroup of J-L862, L147.1 (age estimate 5631-6778yBP yBP): YSC235>PF4847/CTS11741>YSC234>ZS241>ZS227>Z18271 (age estimate 2731yBP).[53]

For people with European maternal ancestry, mtDNA tests are offered to determine which of eight European maternal "clans" the direct-line maternal ancestor belonged to. This mtDNA haplotype test was popularized in the book The Seven Daughters of Eve.

Genealogical DNA tests have become popular due to the ease of testing at home and their usefulness in supplementing genealogical research. Genealogical DNA tests allow for an individual to determine with high accuracy whether he or she is related to another person within a certain time frame, or with certainty that he or she is not related. DNA tests are perceived as more scientific, conclusive and expeditious than searching the civil records. However, they are limited by restrictions on lines that may be studied. The civil records are always only as accurate as the individuals having provided or written the information.

Y-DNA testing results are normally stated as probabilities: For example, with the same surname a perfect 37/37 marker test match gives a 95% likelihood of the most recent common ancestor (MRCA) being within 8 generations,[54] while a 111 of 111 marker match gives the same 95% likelihood of the MRCA being within only 5 generations back.[55]

As presented above in mtDNA testing, if a perfect match is found, the mtDNA test results can be helpful. In some cases, research according to traditional genealogy methods encounters difficulties due to the lack of regularly recorded matrilineal surname information in many cultures (see Matrilineal surname).[45]

Autosomal DNA combined with genealogical research has been used by adoptees to find their biological parents,[56] has been used to find the name and family of unidentified bodies[57] and by law enforcement agencies to apprehend criminals.[58]

Common concerns about genealogical DNA testing are cost and privacy issues.[59] Some testing companies[60] retain samples and results for their own use without a privacy agreement with subjects.[61][62]

Autosomal DNA tests can identify relationships with good accuracy out to about 2nd cousin,[63] but they have limitations.[64][65][66] In particular, transplants of stem cell or bone marrow will produce matches with the donor. In addition, identical twins (who have identical DNA) will share higher amounts of DNA with a greater range of relatives.[67]

Testing of the Y-DNA lineage from father to son may reveal complications, due to unusual mutations, secret adoptions, and false paternity (i.e., that the perceived father in a generation is not the father indicated by written birth records).[68] According to the Ancestry and Ancestry Testing Task Force of the American Society of Human Genetics, autosomal tests cannot detect "large portions" of DNA from distant ancestors because it has not been inherited.[69]

With the increasing popularity of the use of DNA tests for ethnicity tests, uncertainties and errors in ethnicity estimates are a drawback for Genetic genealogy. While ethnicity estimates at the continental level should be accurate (with the possible exception of East Asia and the Americas), sub-continental estimates, especially in Europe, are often inaccurate. Customers may be misinformed about the uncertainties and errors of the estimates.[70]

Some have recommended government or other regulation of ancestry testing to ensure its performance to an agreed standard.[71]

A number of law enforcement agencies attempt to coerce genetic genealogy companies that store customer's data into giving up information on their customers who could match cold case crime victims[72] or perpetrators. A number of companies fight the requests.[73] The Contra Costa County District Attorney's office used the "open-source" genetic genealogy site GEDmatch to find a relative of the suspect in the Golden State Killer case.[74][75]

Though genealogical DNA test results in general have no informative medical value and are not intended to determine genetic diseases or disorders, a correlation exists between a lack of DYS464 markers and infertility, and between mtDNA haplogroup H and protection from sepsis. Certain haplogroups have been linked to longevity in some population groups.[76][77]

The testing of full mtDNA sequences is still somewhat controversial as it may reveal medical information. The field of linkage disequilibrium, unequal association of genetic disorders with a certain mitochondrial lineage, is in its infancy, but those mitochondrial mutations that have been linked are searchable in the genome database Mitomap.[78] The National Human Genome Research Institute operates the Genetic And Rare Disease Information Center[79] that can assist consumers in identifying an appropriate screening test and help locate a nearby medical center that offers such a test.

Some[which?] genealogy software programs allow recording DNA marker test results, allowing for tracking of both Y-chromosome and mtDNA tests, and recording results for relatives.[80] DNA-family tree wall charts are available.

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What Are the Uses for Genetic Tests? – Verywell Health

May 5th, 2018

As scientific and medical discoveries help us better understand how our genetic makeup affects our bodies and our health, new tests are also being developed to help individuals know whether their genes align with certain diseases or conditions. People have begun to wonder whether they should undergo genetic testing. That decision can be made by understanding what genetic testing is all aboutand reviewing the pros and cons of genetic testing.

For thousands of years, human bodies have developed diseases or conditions with very little knowledge about why. Why does one woman develop breast cancer, but another one does not? Why does one man develop Parkinson's disease, but another does not? While environmental factors could tell part of the story, it was recognized that there must be something about that person's body that contributed to the development of these medical problems, too.

Early development of medical science was mostly aimed at making sure diseases and conditions could be cured or healed. During the past 50 or 60 years, science began looking at a person's genetic makeup as a way to answer more fundamental questions about why humans varied in their development of these kinds of problems.

Other human body questions developed over time, too, often in response to legal questions. Questions like, who fathered a particular baby? Or whose blood was found on a murder weapon?

Beginning in the 1950s and '60s when DNA was discovered as the basis of human cells, and genes were discovered as the basis for DNA and heredity, and therefore no two human beings had exactly the same genes or DNA, scientists realized they could begin to answer some of those questions. For example, if they examined the genetic makeup of a group of people who had the same disease, they could come to some conclusions about the similarities of their genes, and why their genes were different from someone who did not have that disease. Or, if they mapped someone's DNA, they could compare it to someone else's DNA and know whether the two people were related.

By 2003, the Human Genome Project was completed, and scientists were able to identify every gene in a human's body. Other scientists began pairing them with the medical problems they cause. Among the earliest disease-identifiable genes were the BRCA genes, known to influence development of breast cancer. More new gene-disease identifications are being made every day.

As these pairings are discovered, scientists can begin to see how they influence development of disease or conditions, and can, hopefully, someday then develop ways to stop those genes from their destiny of creating those medical problems. These are the early days of personalized medicine. Personalized medicine means a person's genetic makeup is what influences either preventive steps to avoid disease, or drugs or other medical treatments that are tailored to a person based on their genetic makeup.

What Types of Genetic Tests Exist?

Some genetic tests have been around for decades. The testing of blood, saliva, hair and skin has been done for decades to determine everything from "whodunnit?" to paternity.

Others have been in use for several years. Genetic screening tests may take place before a baby is conceived to make determinations about whether parents' offspring will be prone to develop certain diseases or conditions. Prior to insemination, a woman and man will both undergo genetic testing to determine whether or not their baby will develop a genetic disease like cystic fibrosis, sickle cell, or Huntington's disease. Once they know the chances, they can better determine whether they should conceive that baby.

Today new tests are being developed for many types of diseases that may improve our knowledge of our health histories and possibly predict our health futures. Tests have been developed to determine someone's risk for developing Alzheimer's disease, high blood pressure, or lung cancer, or for example. These kinds of tests are in their infancy, and for most, scientists disagree on their accuracy.

Why Are There Questions About the Pros and Cons of Genetic Testing?

There are very few questions about the reliability of genetic testing for blood evidence, parent identification or pre-natal determinations because they are quite definitive and have already proved themselves to be useful.

Questions arise for those tests which have not yet proven their value. Even when a gene can be aligned with a certain disease, and even if it can be determined that someone possesses that version of a gene, that does not guarantee that person will develop the disease. Even if it could prove someone will develop the disease, there may be no way to alter that development or even treat them if they do develop it. Those are factors which influence the tests' value.

Scientists and researchers are definitely interested in making sure genetic testing takes place as they develop more and more approaches to personalized medicine. The more testing that takes place, the more evidence they have for procedures, processes, and treatments that may or may not work.

But today, there is little medical value for patients to have their genes tested in regards to future disease development. There are a few exceptionsthose aimed at identifying breast and other female cancers, for example. Over time, new, more definite tests and next steps will be developed for even more diseases and conditions.

Therefore, questions arise about whether or not someone should have their genes screened for these types of diseases today. You'll want to be aware of the pros and cons to genetic testing.

What Are the Pros of Genetic Testing?

For those tests that are already in regular use, like paternity or pre-natal genetic testing, there are well-document positive outcomes. They put people in control of information that helps them make solid decisions about their future medically, financially and legally. Having that kind of definitive knowledge is a definite pro for many people.

This is also true for those genetic tests that are in use for some disease predictions, such as the BRCA testing. Women who learn they have specific indicators and a good chance that they will develop the disease can make decisions based on that knowledge.

And that is the most important "pro" for any genetic testingknowledge. If you are someone who just wants to know about possibilities so you can make decisions, then you might want to have the testing. For example, you might be tested for genetic markers for Alzheimer's Disease. If you learn your body will have a tendency to develop Alzheimer's Disease, you might make preventive choices in your younger years to give yourself the best chance of not developing it.

One other positive outcome is that by having your genes screened, your information will be put into a database of information which can be shared by researchers and scientists around the world. They are learning more about how to use this information to develop treatment to help our children, their children and so forth in the future. In fact, some people are willing to undergo testing simply to further science, in hopes it will benefit their descendants.

What Are the Cons of Genetic Testing?

Because most of the world of genetic testing and personalized medicine is so new, there are still many questions it cannot address. Also, since most genetic testing only raises more questions, instead of providing answers, it may actually create more problems than it solves. Further, there are a number of legal and ethical implications surrounding genetic testing, most of which lean toward the negative.

Here are the questions which suggest those potential problems:

As time goes on, more tests will be developed, more laws will be created to address them, and personalized medicine will become an effective approach to treating human beings for medical problems. But for now, patients must review the pros and cons of genetic testing for themselves to decide whether it is the right step for them.

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What Are the Uses for Genetic Tests? - Verywell Health

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Best DNA Testing Kits 2018 – Genetic Testing for Ancestry …

May 5th, 2018

Why Trust Us?I spoke with DNA experts from the National Society of Genetic Counselors, Ancestry.com and with CeCe Moore, the DNA expert for PBSs Finding Your Roots. I spent more than 15 hours researching dog DNA tests, DNA health and fitness tests and paternity tests. I also spent more than 20 hours researching ancestry DNA tests alone. I swabbed and spat to submit my DNA to seven ancestry DNA companies and spent hours browsing my results from each company.

There are many different DNA tests for sale right now. As Brianne Kirkpatrick, a certified genetic counselor by the National Society of Genetic Counselors and founder of private DNA consulting company WatershedDNA told us, It can be hard to know as a consumer which test is best for you, because there are many different things that can come from testing and each company provides a slightly different offering.

We focused our research and testing on tests that consumers can easily take or administer in the privacy of their homes. I took all of the ancestry DNA tests myself, just as a consumer would, by signing up and paying for the services directly. We didnt have access to any premium features or portals that regular consumers dont have and we researched and cold-called companies as if we were normal people.

Top Ten Reviews has been reviewing tech products for over a decade, and weve been reviewing DNA products for over a year. I am an experienced writer and reviewer and I have tested and written reviews for many digital products and services for Top Ten Reviews.

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Best DNA Testing Kits 2018 - Genetic Testing for Ancestry ...

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Employees Jump at Genetic Testing. Is That a Good Thing …

April 21st, 2018

While regulators called their decision a step forward in the availability of direct-to-consumer genetic screening, they explicitly warned that the test did not detect most mutations that increase breast cancer risk. They also warned consumers not to use the tests as a substitute for qualified medical care and genetic counseling.

Color, the genomics company, takes something of a middle road. It markets comprehensive medical diagnostic tests that screen for all mutations of certain genes known to be linked to certain kinds of heredity cancers and heart risks. It has doctors available to order its tests online for users and provides genetic counseling to discuss users results.

By using genetics, you can help some people prevent or interrupt something at an earlier stage where the costs are much lower, said Othman Laraki, chief executive of Color Genomics. The start-up advises users that they could develop major diseases even if their test results show no harmful mutations.

Executives at SAP and Nvidia said they hoped genetic screening might ultimately help prevent at least a few late-stage cancers, the kinds of life-threatening illnesses that can debilitate employees and cost companies with self-funded health plans more than $1 million in medical fees.

After Nvidia began offering free screening from Color last year, about 27 percent of its 6,000 eligible employees in the United States took the test. After SAP started subsidizing the genetic tests last year, about 17 percent of the companys 30,000 eligible employees and family members participated.

In the long-term view of a program like this, its going to pay for itself, said Jason J. Russell, who oversees employee compensation and benefits for SAP North America. And, he added, You are creating good will with employees.

Given the expense of screening more people of average risk as well as follow-up costs from additional tests, medicines, surgery and potential complications from surgeries experts said that overall medical expenditures were actually likely to increase. Even so, they said, spending on screening for conditions like hereditary high cholesterol, which increases risk for strokes and heart attacks before the age of 50, could ultimately prolong some lives.

You are getting good preventive care value for money, said David L. Veenstra, a professor at the University of Washington who studies health outcomes and economics.

Color has raised $150 million from venture capital firms like General Catalyst as well as Bay Area tech luminaries including Max Levchin, a PayPal co-founder; Sundar Pichai, Googles chief executive; and Laurene Powell Jobs, a philanthropist-investor who is the widow of the Apple co-founder Steve Jobs.

The company has reduced genetic testing costs by using robotics and machine learning and eliminating tasks like in-person prescreening by doctors. It charges $249 for hereditary risk screening for eight of the most common cancers and began offering that price while more established medical diagnostics firms were charging $4,000 for similar tests.

The price point appealed to OpenTable. It started offering genetic screening benefits after an employee with a history of cancers told executives she was spending thousands of dollars out of her own pocket to pay for hereditary risk tests.

This was a really interesting opportunity to provide some choice to our employees that was accessible and affordable so they could better understand their own personal health, said Christa Quarles, chief executive of OpenTable.

As for privacy concerns, executives at several companies said that Color regularly sent them aggregated data on the number of employees with harmful disease mutations, but that the data is not tied to identifying details like employees names or birth dates.

As more large-scale research is conducted, medical recommendations may change. More than 150,000 patients, for instance, have enrolled in a DNA sequencing study at Geisinger Health, a medical center in Danville, Pa. And the federal advisory panel is updating its recommendation on genetic screening for certain breast cancer mutations.

Executives at several companies that have signed up with Color said they were aware of the debate over genetic screening, but said they believed the start-up was simply ahead of the curve.

Over time, innovation becomes consensus science, said Mr. Russell of SAP.

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Genetic testing – Mayo Clinic

April 17th, 2018

Overview

Genetic testing involves examining your DNA, the chemical database that carries instructions for your body's functions. Genetic testing can reveal changes (mutations) in your genes that may cause illness or disease.

Although genetic testing can provide important information for diagnosing, treating and preventing illness, there are limitations. For example, if you're a healthy person, a positive result from genetic testing doesn't always mean you will develop a disease. On the other hand, in some situations, a negative result doesn't guarantee that you won't have a certain disorder.

Talking to your doctor, a medical geneticist or a genetic counselor about what you will do with the results is an important step in the process of genetic testing.

When genetic testing doesn't lead to a diagnosis but a genetic cause is still suspected, some facilities offer genome sequencing a process for analyzing a sample of DNA taken from your blood.

Everyone has a unique genome, made up of the DNA in all of a person's genes. This complex testing can help identify genetic variants that may relate to your health. This testing is usually limited to just looking at the protein-encoding parts of DNA called the exome.

Genetic testing plays a vital role in determining the risk of developing certain diseases as well as screening and sometimes medical treatment. Different types of genetic testing are done for different reasons:

Generally genetic tests have little physical risk. Blood and cheek swab tests have almost no risk. However, prenatal testing such as amniocentesis or chorionic villus sampling has a small risk of pregnancy loss (miscarriage).

Genetic testing can have emotional, social and financial risks as well. Discuss all risks and benefits of genetic testing with your doctor, a medical geneticist or a genetic counselor before you have a genetic test.

Before you have genetic testing, gather as much information as you can about your family's medical history. Then, talk with your doctor or a genetic counselor about your personal and family medical history to better understand your risk. Ask questions and discuss any concerns about genetic testing at that meeting. Also, talk about your options, depending on the test results.

If you're being tested for a genetic disorder that runs in families, you may want to consider discussing your decision to have genetic testing with your family. Having these conversations before testing can give you a sense of how your family might respond to your test results and how it may affect them.

Not all health insurance policies pay for genetic testing. So, before you have a genetic test, check with your insurance provider to see what will be covered.

In the United States, the federal Genetic Information Nondiscrimination Act of 2008 (GINA) helps prevent health insurers or employers from discriminating against you based on test results. Under GINA, employment discrimination based on genetic risk also is illegal. However, this act does not cover life, long-term care or disability insurance. Most states offer additional protection.

Depending on the type of test, a sample of your blood, skin, amniotic fluid or other tissue will be collected and sent to a lab for analysis.

The amount of time it takes for you to receive your genetic test results depends on the type of test and your health care facility. Talk to your doctor, medical geneticist or genetic counselor before the test about when you can expect the results and have a discussion about them.

If the genetic test result is positive, that means the genetic change that was being tested for was detected. The steps you take after you receive a positive result will depend on the reason you had genetic testing.

If the purpose is to:

Talk to your doctor about what a positive result means for you. In some cases, you can make lifestyle changes that may reduce your risk of developing a disease, even if you have a gene that makes you more susceptible to a disorder. Results may also help you make choices related to treatment, family planning, careers and insurance coverage.

In addition, you may choose to participate in research or registries related to your genetic disorder or condition. These options may help you stay updated with new developments in prevention or treatment.

A negative result means a mutated gene was not detected by the test, which can be reassuring, but it's not a 100 percent guarantee that you don't have the disorder. The accuracy of genetic tests to detect mutated genes varies, depending on the condition being tested for and whether or not the gene mutation was previously identified in a family member.

Even if you don't have the mutated gene, that doesn't necessarily mean you'll never get the disease. For example, the majority of people who develop breast cancer don't have a breast cancer gene (BRCA1 or BRCA2). Also, genetic testing may not be able to detect all genetic defects.

In some cases, a genetic test may not provide helpful information about the gene in question. Everyone has variations in the way genes appear, and often these variations don't affect your health. But sometimes it can be difficult to distinguish between a disease-causing gene and a harmless gene variation. These changes are called variants of uncertain significance. In these situations, follow-up testing or periodic reviews of the gene over time may be necessary.

No matter what the results of your genetic testing, talk with your doctor, medical geneticist or genetic counselor about questions or concerns you may have. This will help you understand what the results mean for you and your family.

Explore Mayo Clinic studies testing new treatments, interventions and tests as a means to prevent, detect, treat or manage this disease.

Jan. 06, 2018

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Genetic testing - Mayo Clinic

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Genetic Testing | HealthyWomen

March 19th, 2018

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Overview

What Is It?Genetic testing is used to confirm the presence of genetic diseases, as well as to measure your risk of developing a disease or of passing along a genetic disorder to a child.Today, there are hundreds of genetic tests, some of them for relatively common disorders, such as cystic fibrosis, and others for very rare diseases. A genetic test is fundamentally different from other kinds of diagnostic tests you might take. Indeed, a whole new field, genetic counseling, has grown up around the need to help incorporate family history and genetic testing into modern health care.

The purposes of genetic tests vary. Some genetic tests are used to confirm a preliminary diagnosis based on symptoms. But others measure your risk of developing a disease, even if you are healthy now (presymptomatic testing), or determine whether you and your partner are at risk of having a child with a genetic disorder (carrier screening).

As the name suggests, a genetic test looks at your genes, which consist of DNA (deoxyribonucleic acid). DNA is a chemical message to produce a protein, which has a specific function in the body. Proteins are essential to lifethey serve as building blocks for cells and tissues; they produce energy and act as messengers to make your body function. In addition to studying genes, genetic testing in a broader sense includes biochemical tests for the presence or absence of key proteins that signal aberrant gene function.

What do Genetic Tests Test For?

Chromosome AbnormalitiesLong strings of DNA condense together, packaging the DNA in the form of a chromosome. Most people have 23 pairs of chromosomes in the nucleus of each cell. One of each chromosome pair is inherited from the mother and the other is inherited from the father. Some tests look at chromosomes for abnormalities such as extra, missing or transposed chromosomal material. The chromosomes hold 20,000 to 25,000 genes, meaning that each chromosome is densely packed with genes. Extra or missing pieces of chromosomes can have a significant impact on the health of an individual. Also, sometimes pieces of chromosomes become switched, or transposed, so that a gene ends up in a location where it is permanently and inappropriately turned on or off. The genes on the chromosomes are responsible for making proteins, which direct our biological development and the activity of about 100 trillion cells in our bodies.

If something goes wrong with an essential protein, the consequences can be severe. For example, a protein called alpha-1 antitrypsin (AAT) clears the lungs of a caustic agent called neutrophil elastase. If the body has an alteration in the gene that makes the protein AAT, the AAT protein may not be made correctly or at all. Then neutrophil elastase will build up in the lungs, and the individual can develop emphysema and other complications.

MutationsMost genetic conditions are the result of mutations in the DNA, which alter the instructions for making a given protein. Some mutations are inherited on genes passed down from parents, while others occur during an individual's lifetime. These mutations can lead to diseases ranging from those we think of as "genetic diseases," such as cystic fibrosis or AAT deficiency, to those we think of as degenerative diseases, such as heart disease. In the case of diseases like heart disease, asthma or diabetes, a combination of factorssome genetic, some related to environmental or lifestylemay work together to trigger the disease.

It's possible to have a mutation, even one for a severe disease, such as cystic fibrosis (CF) and never know it. Almost all humans have two copies of each chromosome and therefore have two copies of each gene, one inherited from the mother and the other from the father. If only one copy of a given gene has a mutation, you are a healthy carrier of the disorder. You "carry" the mutation but do not have the disease. If both copies of a gene have a mutation, you will have the disease. Such disorders are called autosomal recessive. If you are a carrier, the unaltered gene in the pair retains the function. Those who are diagnosed with a recessive disease have inherited two copies of a gene, both carrying a mutation. Therefore, since one of those copies came from the mother and the other from the father, both parents must have at least one copy of the gene with a mutation. If two carriers of the same disease-causing gene have children, each pregnancy has a 25 percent chance of having the disease (because of a 25 percent chance of inheriting both the mother's and the father's mutated copies of the gene), a 50 percent chance of being a carrier and a 25 percent chance of not inheriting the mutation at all.

Some disorders, such as Huntington disease, are autosomal dominant. If a person has one mutated gene, its effects will cause the disease, even if the matching gene is normal. Thus, each child of a parent with Huntington disease has a 50 percent chance of inheriting the gene causing the disease. Osteogenesis imperfecta, which causes brittle bones, is another example of a dominant disorder.

Chromosomes can be one of two types: sex chromosomes or autosomes. Sex chromosomes are X and Y. Most men have an X and a Y, and most women have two Xs. If each parent contributes an X chromosome, the child is a girl; if the father passes on his Y chromosome, the child is a boy. Because girls have two X chromosomes, and therefore two copies of every X-linked gene, they are less likely than boys to have symptoms from X-linked genetic diseases because boys don't have a backup copy if an X-chromosome gene has a mutation. Examples of X-linked diseases include forms of hemophilia and fragile X syndrome (the most common inherited cause of mental impairment). Autosomes are the remaining 22 pairs of chromosomes. Therefore, most diseases are autosomal, or due to genes on the autosomes.

What Genetic Tests Can Find

Unclear Results Although genetic testing can be very useful in diagnosis, prevention and medical decision-making, genetic tests do not always provide clear answers. One such result is a "variant of uncertain significance." All people have differences in their DNA, so if a new DNA alteration is detected, it may be uncertain as to whether it is associated with disease or is part of normal human variation. Another limitation is that not all genetic tests are created as equals. Since genetic testing can be very expensive, some tests only look for the most common disease-causing mutations. Instead of examining the entire gene, these tests only look for specific, common mutations. If you or your family has a mutation in a portion of the gene that wasn't tested, you will have a negative result, even though you do have a disease-associated mutation. Since genetic tests are not perfect, it is always important that genetic test results be interpreted in combination with medical and family history by a genetic counselor or other genetics-credentialed professional.

The Cost of Genetic Testing

The cost of a genetic test varies dramatically, ranging from $100 to more than $3,200. The difference stems largely from the variation in labor intensity of different tests. Some tests look for a limited number of mutations (sometimes only one) known to cause a disease. This type of test may only look at one piece of DNA code, for one specific mutation. Other genetic tests require sequencing of the entire gene, where they examine each piece of DNA code comprising the gene, which can be thousands of pieces of code.

The explosion of genetic research now taking place is expected to bring prices down and dramatically increase the number of tests available. Tests are becoming available to predict your genetic risk of more common disease, such as heart disease and diabetes. This information will help you and your health care professional develop specific strategies for prevention. Preventive efforts can include changing your lifestyle or perhaps taking certain medications, which may be tailored to your specific genetic profile, and early screening to head off the worst complications should you develop the disease.

Facts to Know

A genetic test examines some aspect of a person's genetic makeup, either directly through gene sequencing or indirectly through the measure of marker chemicals. Such a test usually aims to determine whether a person has, is at above-average risk of having or is a carrier of a disease-causing genetic mutation.

Because the nature of genetic testing is so complex, with implications for both the person being tested and his or her family, genetic counseling is desirable before taking any genetic test and essential for proper interpretation of test results.

Genetic counselors are committed to protecting your privacy. They will not contact other family members without your permission, though they may encourage you to share results that might affect your relatives.

A maternal serum screening test indicates whether a fetus is at above-average risk of being born with certain genetic disorders, most notably Down syndrome, trisomy 18 and open neural tube defects. The test is not diagnostic and a positive result is usually followed up with a diagnostic amniocentesis or chorionic villus sampling test. Out of 1,000 serum screening tests, 50 will suggest increased risk for open neural tube defects, but only one or two of the fetuses will have such a defect. Likewise 40 of 1,000 will test positive for increased risk of Down syndrome, but only one or two will fetuses will actually have the disease.

Some genetic disorders are recessive and X-linked, which means they are caused by a mutation in a gene that resides on the X chromosome. Females have two X chromosomes, but males have only one. If a mother has a disease-linked recessive gene mutation in one of her X chromosomes, she is a carrier of the disorder but will have no or minimal symptoms herself. If she has a son, he will have a 50 percent risk of inheriting the disorder; a daughter will have a 50 percent chance of being a carrier.

In addition to disorders that have surfaced in your family, you may want to consider carrier testing for genetic conditions that occur with greater frequency in your particular ethnic group. For example, Caucasians have a higher risk of cystic fibrosis, while those of African descent are at high risk of carrying a mutation that can cause sickle cell disease. A battery of tests exists for those of Ashkenazi (Eastern European) Jewish descent. Remember that the best time for carrier testing is before a pregnancy.

Children should not be screened for carrier status or for diseases that won't trouble them until much later in life because the information is not relevant to their health care. Most geneticists and genetic counselors consider such testing unethical, since children are not in the position to make their own decisions as to whether or not they want the test (known as informed consent).

Within a family, two or more incidences of the same type of cancer or related cancers, or one at under age 50 may indicate a hereditary pattern. A genetic counselor can take a closer look at your family history to determine whether an inherited mutation appears to be responsible for the cancers in your family and can advise you as to whether testing is available.

The best-known cancer predisposition tests look for mutations in the BRCA1 and BRCA2 genes. Women with a BRCA mutation face a lifetime breast cancer risk of up to 88 percent, compared to about 13 percent in the general population, and lifetime ovarian cancer risk of up to 60 percent, compared to a population risk of about 1.4 percent.

If your family has a history of colorectal and related cancers, you may want to consider genetic counseling and risk assessment. Several colorectal cancer syndromes can be responsible for hereditary cancer risk. One such syndrome is Lynch Syndrome. The syndrome increases lifetime risk of colorectal cancer to 80 percent vs. a 5.4 percent population risk, but also boosts risk of endometrial cancer (to 60 percent), ovarian cancer (to 12 percent) and gastric cancer (to 13 percent). Those with Lynch Syndrome also face a higher risk of cancers of the kidney and ureter, brain and small bowel.

Questions to Ask

Review the following Questions to Ask about genetic testing so you're prepared to discuss this important health issue with your health care professional.

General

Could my symptoms be caused by a genetic disorder? Is testing available?

Are you experienced in diagnosing and treating genetic disorders? If not can you make a referral?

How accurate is this test?

What are the risks of the test?

What information will come out of the test?

What will a positive or negative result tell me?

Is an uncertain result possible, and what would that mean?

What are my options for preventing or treating the disease if a mutation is found?

What other family members might be affected?

How do I broach the subject with them?

Could this disorder affect my children before they're grown? Should they be tested?

What measures are in place to protect my privacy?

How often have you performed the test?

How experienced is the lab in performing this test?

How long will it take to get results back?

How could this test affect my health care?

Cancer Predisposition Testing

Does my family history suggest a pattern of inherited cancer?

Is there a test available to determine which family members are most at risk?

What are my chances of developing cancer if I test positive for a mutation?

How does my risk change with age?

What are my options if I test positive?

How frequently should I have screenings?

Are preventive measures such as surgery or pharmaceuticals available?

Carrier Screening And Preconception Counseling

Based on family history and ethnicity, which carrier tests should my partner and I consider?

What criteria are you using to determine which tests are right for us?

Would other centers recommend a different lineup of tests?

What are the options if a result suggests the possibility of having a child with a genetic disorder?

Prenatal Testing

How early or late in my pregnancy can this test be performed?

What are the risks of the test?

Is this a risk screening test or a diagnostic test?

What are the options if the test finds a problem?

Key Q&A

What is genetic testing?

A genetic test looks at a particular aspect of your genetic makeup, either directly through gene sequencing or indirectly through measure of marker chemicals. Testing may be done for a variety of purposes:

Diagnosis, to determine if a person has a genetic disorder (often performed in conjunction with analysis of symptoms)

Risk screening, to determine if a person is at increased risk of having a genetic disorder (with follow-up diagnostics usually called for if a test is positive)

Predisposition testing, to determine if a person is at higher risk of developing a particular disease later in life

Carrier testing, to determine if a person is a carrier of a disease-causing mutation and may be at risk of having a child with the disease

What does it mean if I'm a carrier for a disease?

Genes come in pairs, and a carrier of a recessive disease has one mutated, disease-causing gene and a corresponding normal gene. The normal gene compensates for the mutated copy and the person never develops the disease. If two carriers of the same disease-causing gene have a child, however, that child has a 25 percent chance of having the disease (because of a 25 percent chance of inheriting two mutated copies of the gene), a 50 percent chance of being a carrier and a 25 percent chance of not inheriting the mutation at all.

If my partner and I have carrier testing, will the results tell us whether or not our children will be affected?

In most cases, the test will provide only guidance as to your child's risk for being born with a particular disorder or being a carrier of the disease. Because you contribute only one of the two copies you have of each gene, each child has a 50 percent chance of inheriting any particular mutation from you. Each child likewise has a 50 percent chance of inheriting any particular mutation your partner has. Thus, if you are both carriers of the same autosomal recessive disorder, each child has a 25 percent risk of being born with the disease, a 50 percent risk of being a carrier and a 25 percent chance of not inheriting a mutation at all. A genetic counselor can help you sort through the possible combinations in your situation and describe options for pregnancy planning and prenatal testing.

Why do I need a genetic counselor in addition to my doctor?

Most counselors and geneticists have extensive training and certification specifically related to genetics and genetic testing. Additionally, most physicians do not have time to spend an hour or more providing education, information collection, risk assessment and informed consent. Hence, many physicians make referrals when the issue arises. Genetic counselors usually work with geneticists (MDs or PhDs), particularly for more complex cases.

If I have a test, will I face job or insurance discrimination if the result is positive?

The Genetic Information Nondiscrimination Act of 2008 (GINA), a new federal law that protects Americans from being treated unfairly because of genetic diseases and mutations that may affect their health, was recently passed. This law specifically addresses protections in regard to health insurance and the workplace.

Why are some genetic tests so much more expensive than others?

Some tests look for mutations by actually sequencing the entire gene; these tests, which may cost more than $3,000, look for mutations by determining the exact order of the chemicals that comprise the gene and compare the order to that of a normal gene. Other, less expensive tests look for individual, commonly known disease-causing mutations. It's like going to a grocery store. If you have never been to that store before and you are looking for a bottle of ketchup, you may go through every aisle. This is the equivalent of sequencing; looking through the entire gene for the mutation. If you have been there before and know where the ketchup is, you can go directly to the location in the store, which is like specific point mutation testingyou know exactly where the mutation is located.

A relative has canceram I at risk, too?

Your family history provides the best clues. Two or more relatives with early onset (before age 50 or 60, depending on the cancer) of related cancers or diagnosis of two or more related cancers in the same person suggest the possibility of a genetic link that could put you at risk. Related cancers are not always as obvious as you might think. For example, colon cancer and endometrial cancer can be caused by the same genetic mutation. Talk to a genetic counselor to get a better idea of your risk and find out whether predisposition testing is available.

Isn't my health my own business? Why should my extended family be involved?

By their very nature, genetic diseases are a family affair, with mutations passed on to multiple generations. When a disease is clearly hereditary, testing positive for a disease-causing mutation or being diagnosed with the disease provides knowledge that other family members may be at risk. A genetic counselor can help you identify who may be at risk and should be notified and can help you handle the situation if there is estrangement between relatives.

What's the difference between amniocentesis and chorionic villus sampling? How do I decide which is right for me?

Both procedures provide for diagnosis of specific chromosomal and genetic disorders in the fetus. Amniocentesis is more likely to be offered as a follow-up to an abnormal maternal serum screening test because results of the screen are obtained too late in pregnancy for CVS. However, CVS, which is done at 10 to 12 weeks gestation, or amniocentesis, are offered in the following situations:

You will be 35 or older at delivery.

A genetic disorder has surfaced on either side of the family.

You or your partner has had a previous child with a birth defect.

You and your partner are carriers of the same recessive disorder.

Both chorionic villus sampling (CVS) and amniocentesis can cause cramping, and a small number of women have miscarriages following the procedures (the risk is higher with CVS). It takes one to two weeks to get results from either test.

Amniocentesis is performed more frequently and should be the choice if you're at risk having a child with neural tube defects. The procedure is performed at 15 to 18 weeks of pregnancy.

CVS can be performed earlier, at 10 to 12 weeks, and is popular with parents who would like to know results before the pregnancy starts to show. The procedure is not available everywhere, however.

If I get a negative result from a cancer predisposition test, can I still develop that particular kind cancer?

Yes. Your lifetime risk for breast cancer, even in the absence of a gene mutation, is about 12 percent. At least 90 percent of breast cancer is not due to a single, inherited cancer predisposition gene. A negative BRCA test result simply means you don't face a higher-than-average risk for the disease due to a hereditary cancer syndrome.

Genetic Counseling

What Is Genetic Counseling?

Because the nature of genetic testing is so complex, with implications for both the person being tested and his or her family, genetic counseling is an important part of pre- and post-genetic testing. Unlike most medical appointments, a counseling session may be a family affair, with participation of all concerned relatives.

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Genetic Testing | HealthyWomen

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Prenatal Genetic Screening Tests – ACOG

March 17th, 2018

Pregnancy

Prenatal genetic testing gives parents-to-be information about whether their fetus has certain genetic disorders.

Genetic disorders are caused by changes in a persons genes or chromosomes. Aneuploidy is a condition in which there are missing or extra chromosomes. In a trisomy, there is an extra chromosome. In a monosomy, a chromosome is missing. Inherited disorders are caused by changes in genes called mutations. Inherited disorders include sickle cell disease,cystic fibrosis, TaySachs disease, and many others. In most cases, both parents must carry the same gene to have an affected child.

There are two general types of prenatal tests for genetic disorders:

Both screening and diagnostic testing are offered to all pregnant women.

Screening tests can tell you your risk of having a baby with certain disorders. They include carrier screening and prenatal genetic screening tests:

First-trimester screening includes a test of the pregnant womans blood and an ultrasound exam. Both tests usually are performed together and are done between 10 weeks and 13 weeks of pregnancy:

Second-trimester screening includes the following tests:

The results from first- and second-trimester tests can be combined in various ways. Combined test results are more accurate than a single test result. If you choose combined screening, keep in mind that final results often are not available until the second trimester.

Cell-free DNA is the small amount of DNA that is released from the placenta into a pregnant womans bloodstream. The cell-free DNA in a sample of a womans blood can be screened for Down syndrome, trisomy 13, trisomy 18, and problems with the number of sex chromosomes. This test can be done starting at 10 weeks of pregnancy. It takes about 1 week to get the results. A positive cell-free DNA test result should be followed by a diagnostic test with amniocentesis or CVS.

The cell-free DNA screening test works best for women who already have an increased risk of having a baby with a chromosome disorder. For a woman at low risk of having a baby with a chromosome disorder, conventional screening remains the most appropriate choice. Cell-free DNA testing is not recommended for a woman carrying more than one fetus.

Results of blood screening tests for aneuploidy are reported as the level of risk that the disorder might be present:

Diagnostic testing with CVS or amniocentesis that gives a more definite result is an option for all pregnant women. Your obstetrician or other health care professional, such as a genetic counselor, will discuss what your screening test results mean and help you decide the next steps.

With any type of testing, there is a possibility of false-positive results and false-negative results. A screening test result that shows there is a problem when one does not exist is called a false-positive result. A screening test result that shows there is not a problem when one does exist is called a false-negative result. Your health care professional can give you information about the rates of false-positive and false-negative results for each test.

It is your choice whether to have prenatal testing. Your personal beliefs and values are important factors in the decision about prenatal testing.

It can be helpful to think about how you would use the results of prenatal screening tests in your pregnancy care. Remember that a positive screening test tells you only that you are at higher risk of having a baby with Down syndrome or another aneuploidy. A diagnostic test should be done if you want to know a more certain result. Some parents want to know beforehand that their baby will be born with a genetic disorder. This knowledge gives parents time to learn about the disorder and plan for the medical care that the child may need. Some parents may decide to end the pregnancy in certain situations.

Other parents do not want to know this information before the child is born. In this case, you may decide not to have follow-up diagnostic testing if a screening test result is positive. Or you may decide not to have any testing at all. There is no right or wrong answer.

Amniocentesis: A procedure in which a needle is used to withdraw and test a small amount of amniotic fluid and cells from the sac surrounding the fetus.

Aneuploidy: Having an abnormal number of chromosomes.

Carrier Screening: A test done on a person without signs or symptoms to find out whether he or she carries a gene for a genetic disorder.

Cell: The smallest unit of a structure in the body; the building blocks for all parts of the body.

Chorionic Villus Sampling (CVS): A procedure in which a small sample of cells is taken from the placenta and tested.

Chromosomes: Structures that are located inside each cell in the body and contain the genes that determine a persons physical makeup.

Cystic Fibrosis: An inherited disorder that causes problems in digestion and breathing.

Diagnostic Tests: Tests that look for a disease or cause of a disease.

DNA: The genetic material that is passed down from parents to offspring. DNA is packaged in structures called chromosomes.

Down Syndrome: A genetic disorder that causes abnormal features of the face and body, medical problems such as heart defects, and intellectual disability. Most cases of Down syndrome are caused by an extra chromosome 21 (trisomy 21). Many children with Down syndrome live to adulthood.

Fetus: The stage of prenatal development that starts 8 weeks after fertilization and lasts until the end of pregnancy.

Genes: Segments of DNA that contain instructions for the development of a persons physical traits and control of the processes in the body. It is the basic unit of heredity and can be passed down from parent to offspring.

Genetic Counselor: A health care professional with special training in genetics and counseling who can provide expert advice about genetic disorders and prenatal testing.

Genetic Disorders: Disorders caused by a change in genes or chromosomes.

Inherited Disorders: Disorders caused by a change in a gene that can be passed down from parent to children.

Monosomy: A condition in which there is a missing chromosome.

Mutations: Permanent changes in genes that can be passed on from parent to child.

Neural Tube Defects: Birth defects that result from incomplete development of the brain, spinal cord, or their coverings.

Nuchal Translucency Screening: A test in which the size of a collection of fluid at the back of the fetal neck is measured by ultrasound to screen for certain birth defects, such as Down syndrome, trisomy 18, or heart defects.

Obstetrician: A physician who specializes in caring for women during pregnancy, labor, and the postpartum period.

Placenta: Tissue that provides nourishment to and takes waste away from the fetus.

Screening Tests: Tests that look for possible signs of disease in people who do not have symptoms.

Sex Chromosomes: The chromosomes that determine a persons sex. In humans, there are two sex chromosomes, X and Y. Females have two X chromosomes and males have an X and a Y chromosome.

Sickle Cell Disease: An inherited disorder in which red blood cells have a crescent shape, causing chronic anemia and episodes of pain. It occurs most often in African Americans.

TaySachs Disease: An inherited birth defect that causes intellectual disability, blindness, seizures, and death, usually by age 5 years. It most commonly affects people of Eastern and Central European Jewish, Cajun, and French Canadian descent, but it can occur in anyone.

Trimester: One of the three 3-month periods into which pregnancy is divided.

Trisomy: A condition in which there is an extra chromosome.

Trisomy 13 (Patau Syndrome): A chromosomal disorder that causes serious problems with the brain and heart as well as extra fingers and toes, cleft palate and lip, and other defects. Most infants with trisomy 13 die within the first year of life.

Trisomy 18 (Edwards Syndrome): A chromosomal disorder that causes severe intellectual disability and serious physical problems such as a small head, heart defects, and deafness. Most of those affected with trisomy 18 die before birth or within the first month of life.

Ultrasound Exams: Tests in which sound waves are used to examine internal structures. During pregnancy, they can be used to examine the fetus.

Read the rest here:
Prenatal Genetic Screening Tests - ACOG

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Genetic testing – About – Mayo Clinic

December 27th, 2017